[project]Laser Harp

[genesis]

Ok now my laser projector is finished i can work on another project a laser harp
I have worked on a first version six years ago but a simple one.
Now i have goods and accurate laser scanners and the system can be simplified.
Here are the characteristics of the project
- 8051 core
- LCD for control
- midi interface to use Sk@le tracker or other midi software for playing
- we can choose the color of the note
- we can choose the number of notes
- space beetween notes
- note width
- scan speed
- span
- ILDA interface to the laser.
- frame free (laser reflection system)

all schematic and code are free (open source )

the system work like this:
a DAC generate two signals
one for the scanners and one for the laser intensity or brightness
when the note is drawed the microcontroller test the sensor input.
If this input is active the note drawed at this time is active and the midi “note on” instruction is sended.

Here is a simple functionnal diagram




voilà en fait les esquisses de schémas que j ai utilisé pour router

the symetric power supply and DAC :


the In System Programming schematic for the P89C664:


the microcontroller pinning with some modifications dues to the PCB routing:


the LCD and push buttons drawing


and the theorical schematic of the photodiode amplifier…..i not sure for this part….


now the PCB routing
we see the photodiode amplifier at the top right of the PCB:


the LCD and push buttons card:


i have make the cards without smd component to help of the home made copy

the component box


the PCBs….just cooked :


the main boad card:



power supply and LCD board:



power supply with all components:



the bottom:



all is ok no smoke :




coper protected by solder :


drilling :



start to mount components :



we see the end



the bottom


first test no smoke and the microcontroller reply to isp commands good!


The top of the board finished :


bottom view :


and in the box :


here are some first tests of the sensors. Click on the eye to see them:







the DACs tests :


we see at the top of the scope the position signal for the scanners anda t the bottom the brightness control.
At each step of the position we see the brightness pulse to turn on the laser.

Now after lot of coding some tests and fun






and the firsts tests of the harp in video :















and now i stop the tests because the automatic cooling of the laser start and thats too loud for my neighbour



if there is lot of smoke the sytem can see all notes on but this is when there is lot lot of smoke!!

And a picture of the laser with the latest firmware revision


and his complete boot in video :



now i need to make evolution on code and i have an idea…..change the color of the active note I think that was fun…

to be continued…..

[genesis]

new tests from this afternoon but without sound (for the neighbors)
i have tested an idea to change the color of the active note



and two videos of tests:





that works great

[gento]

My Englisch is Merde ... ..... Schade

Kann jemand Translaten ?

Gento

[genesis]

sorry but i don't speak german and the english is better than french to communicate with german community

[afrob]

ungenau:

OK, jetzt da mein Laserprojektor fertig ist kann ich an einem anderen Projekt weiterarbeiten eine Laserharfe
Ich habe schon vor sechs Jahren an einer ersten Version gearbeitet, die aber einfacher war.
Jetzt habe ich gute und genaue Scanner und das System kann einfacher werden.
Hier die Daten des Projekt:
- 8051 Mikrocontroller
- LCD zur Steuerung
- MIDI Interface um den Sk@le Tracker oder andere MIDI Software zum Spielen zu benutzen
- die Farbe der Noten(=Saiten -afrob) ist einstellbar
- die Anzahl der Noten ist einstellbar
- der Abstand zwischen den Noten
- die Breite der Noten
- Scangeschwindigkeit
- Breite
- ILDA Schnittstelle zum Laser.
- Rahmenlos (basierend auf der Reflektion des Laserstrahls)

Alle Schaltpläne und aller Code sind frei (open source )

Das System funktioniert so:
Ein DA-Wandler erzeugt zwei Signale,
eines für die Scanner und eines für die Intensität oder Helligkeit. Wenn eine Note vom Mikrocontroller gezeichnet wird, wird ein Sensoreingang abgefragt. (an dem eine Photodiode hängt, die das reflektierte Licht misst - afrob)
Ist der Eingang aktiv, ist die derzeit gezeichnete Note aktiv und ein MIDI "Note On" Kommando wird gesendet.

Hier ein einfaches Blockdiagramm:


Das symmetrische Netzteil und der DA-Wandler:

Schaltplan zum In-System-Programmieren des (Mikrocontrollers -afrob) P89C664 :

Das Mikrocontroller Pinout mit einigen Änderungung durch das Entflechten der Leiterplatte

Zeichnung des LCD und der Taster

und der theoretische Aufbau des Photodiodenverstärkers.... bin mir bei dem Teil noch nicht sicher….

jetzt das Platinenlayout
der Photodiodenverstärker ist oben rechts auf der Platine zu sehen:

die LCD und Taster Platine:

ich habe die Platinen ohne SMD Bauteile entworfen um den Nachbau zu hause zu vereinfachen

die Bauteilkiste

die Platinen….frisch gekocht :

die Hauptplatine:


Netzteil und LCD Platine:


Netzteil mit allen Bauteilen:


Die Rückseite:


Alles OK Kein Rauch :


verzinnt :

gebohrt :

Anfang der Bestückung :


Fertig


die Rückseite

erster Test kein Rauch und der Mikrocontroller meldet sich auf die ISP-Kommandos. Gut!


Die Oberseite der Platine fertig:

Rückseite:

und im Gehäuse:

Hier sind ein paar erste Tests des Sensorss. Klicke auf das Auge um sie zu sehen:




Test der DA-Wandler:

oben im Oszilloskop ist das Positionssignal zu sehen, unten die Helligkeitssteuerung.
Bei jedem Schritt ist der Puls im Helligkeitssignal zu sehen, der den Laser anschaltet.

Nun nach viel Programmieren ein paar Tests und Spass


und der erste Test der Harfe im Video:




und jetzt stoppe ich den Test, weil die automatische Kühlung des Lasers angeht und das zu Laut für meine Nachbarn ist


Bei viel Nebel sieht das System alle Noten, aber nur bei sehr viel Nebel!!

Und ein Bild des Laser mit der neuesten Firmwareversion

und das kompllette Booten in einem Video:


jetzt werde ich das Programm verbessern und ich habe noch eine Idee…..die Farbe der aktiven Note zu ändern Ich glaube das wäre Fun...

to be continued…..

Sehr interessantes Projekt! Very interestings project!

Grüsse,
afrob

[genesis]

thanks Afrob
i keep you informed of the evolution

[genesis]

some new tests


and a video



at the end of the video the smoke machine work and the harp play alode due to the smoke

[tschosef]

Hai,

very nice work!!! Remember to Jean Michelle Jare (Chare??)....
Is it working only in darknes? What happens if you swich on the light?

greetings
Erich

[genesis]

yes the song is from jeam michel jarre

yes if you turn on the light the harp play all notes because the sensor work at approx 50Hz to detect laser reflection but the 230v is at 50Hz too.

[tschosef]

hai..

in that case you have to turn of the Movingheads on your first gig

[genesis]

i not really understand what you want to say

[tschosef]

hai,

sorry... my english is not the best.
i want to say: this could be a problem if you use the "Harp" live with light equipment on the stage

greetings
Erich

[genesis]

yes thats true but the harp is used in dark the most of the time
but if the laser has more power and single line you can set less sensibility at the sensor and a dichro.
in this cas i think you can play in light
this harp use the no frame system but if you want to play in light you can use a frame with sensors at the top and in this case the harp can work in light i think.
all the photodiode need to be wired in parallel just two wires are required

[sanaia]

quite interesting project you are doing
But I think, the original did work a little different and had no need for a scanner. Although I'm not quite shure, I guess it used static beams, however, but it was just green.

BTW: there is a way to detect even very few laserlight in extremely bright environments. It is absolutely no problem to detect just a few µW straylight in the bright daylight. I used such a method to messure some straylight in a bright glowing melting furnace, and it worked very well.

But the here used approach of scanning beams complicates the light detection extremly.

[genesis]

hi )
the original use GSI scanner
the use of scanner not complicate the light detection problem.
yes it is possible to find µW in stay light but if the laser pulse are extremly short and with a transimpedance amplifier and inductor feedback.
here the laser is not modulated at this frequency.

the use of scanner offer a free frame system and beam number and color change. an harp without scanner can't do this

and with the ilda interface you can connect any laser on it without laser modification.

i think the use of scanner is the best solution

[genesis]

hello
i have made some improvement of the code and add a midi-in interface
the schematics come as soon as possible

last test video:>><<

[floh]

Hi Genesis

why not use 3 photodiodes each with a different dichro of the base colors red green and blue? so you can select the color the receiver will trigger on. just compare the three color values (your controller knows the scanned color and can compare with the received). It will make you able to operate in background light. On a event you can make blue room light and red harp or green harp in red room or what you want.

Maybe it is possible to use the same scanner to send the beam and receive the reflection. like in a cd-player by using a polarisation cube or just a beam splitter. this will make you able to receive the exact position as the beam is at the moment. it will help to ignore surrounding light and makes you able to scan a lot more pattern.

cool project! don't give up and make it better and better!

[genesis]

dont worry
i can use the harpe in little light because the photodetector use the modulation of the laser light to remove the steady ambiant light

[rheinperchten]

Ja er baut ne Laserharve wie Jan Michelle Jare ,- interessante Sache. Echt gute Idee

[genesis]

Hello
i restart the developpement soon

[genesis]

Hi all
you can found some video when i've used the harp for a demo
my girlfriend was on keyboard

the system set:
http://www.youtube.com/watch?v=p7iSpjHvEG0

http://www.youtube.com/watch?v=7zBLkLR1wjE

playing on harp:
http://www.youtube.com/watch?v=56Os82IEktw

most of the MVIxxx videos:
http://www.youtube.com/user/bbtoff



the schematics are on demand.
the sensor work well without ambiant light. this is because i want to use the harp with a lexel laser without modulation but you can design your sensor.

the binary is a light version but can be modified if you know C and have Keil or free 8051 compiler.

to download the code you needs to use a freeware from atmel (flip)

[goamarty]

You could use a narrowband filter for the exact Laser-Wavelengths, or 3 Filters and Photodiodes, if one Filter with 3 Transmittance Bands is not available/affordable.
The "CD-Player approach" needs polarised Lasers, as it relies on a PBS-Cube and a waveplate, where the reflected light passes two times (before and after its reflected at the disc surface), so its polarisation is rotated 90° and it exits the cube towards the detector. With the waveplate you are not independant of color/wavelength. Without the waveplate you relie on depolarisation in the diffuse reflection at the hand and lose some power in the detected light, but it should be OK. This should be possible with a multicolor beam, if all Lasers have the same polarisation. Withou polarised Lasers you can only use a half-reflecting mirror and lose also half of the power of the laserbeams.

[genesis]

this harp can use three colors of laser that was the problem.
but if i use a narrow band filter like 532nm
a white light can go through (his green spectrum) not?

[goamarty]

Through a filter for 532nm +/- some nm very little of white light comes through. This is similar to a radio receiver which has a narrow-band input filter and picks your favourite radio station out of the air. You could use three separate receivers for lets say 650nm+/-10, 532+/-3 and 473+/-3. DPSS is much more stable than the diodes. These filters are probably not cheap and the spatial filtering using a direction sensitive detector with optics and the scanners could be cheaper.

[genesis]

thank you for theses infos.
perhaps i try the filter solution.
the other way is more complex just to play with ambiant light

[Hatschi]

Halli Hallo

Great job Genesis, I hope to meet you once again in Germany.
How about other colour for the active note like you showed in Regensburg?

Hatschi

[genesis]

i need to work on the binary for that but the hardware is ready
and for the show i've just a 1W green DPSS (rent for the week end)
the cars was too full to take my colour projector.
i think to sell some harp units to buy a pangolin pro or blue DPSS.
this is my dream since some years but i not have enough money for that and i not make laser rent.

i know somebody who sell his laser plans (i have helped this guy for his sensor but i was not aware of his commercial use....) but i think this is not the solution...

[goamarty]

Also if you use just one receive channel für 532nm you could use different mixed colours from cyan to yellow for optical appearance. The receiver would not be influenced by blue or red (laser) light and the sensitivity would only depend on the quality (narrow bandwidth -> price) of your filter.
Would your lasers be polarised for the pbs-cube solution?

[genesis]

my lasers are not polarized and to keep good sensivity i use a large sensitive photodiode. the optical assembly is verry simple but everybody can try different solutions.
i waste lot and lot time to work on great sensor with ambiant light rejection without success.

even with modulated light the use of automatic gain compensation cause a limitation of simultaneous strings played.

the best thing is to use the harp in darkness with large photodiode.
but if i can found a green (532) filter i try this solution

[goamarty]

A broadband, large area receiver can have good gain, but has always bad noise rejection. So you need to reduce the level of unwanted signals ("noise" from ambient light).
You also could do this with a high directivity receiver, like a directional radio link. With some optics and a tube. If you dont have polarised beams, you can use a normal half silvered mirror. You lose 3dB of Transmit-Power (your beams are less visible) and 3dB of receive Power. But you can gain a huge amount of signal-to-noise-ratio. Compare the directivity of a 10° full angle beam to the half sphere of the plain photo diode.
With the combination of both methods you could probably play your harp in bright sunlight.
If you dont want to lead your reception beam path through the scanners, you could still use two black plates to reduce the sensitivity for ambient light, which comes from outside of the plane of your "harp strings", perhaps you could use a laser-line-generator optics backwards to get a 2D plane of sensitivity instead of a 3D half-room.

[genesis]

i know that
when i say "large area" thats less than 25mm²
i've used OPT101 photodiode witha internal amplifier and make lot of tests with it
http://www.icbase.com/pdf/BBR/BBR03860106.pdf
with more or less gain, DC rejection, demodulation, integration, High pass filter etc. i make 3 or 4 schematics and sensors for tests with more or less success.

my harp can use an external sensor through a connector.

[Hatschi]

Halli Hallo

And what about a CCD-Cam as "sensor"?

Hatschi

[genesis]

it can work.
lots of solutions are available.

[stoppi]

Hallo!

Habe mich auch dieser Spielerei angenommen, jedoch auf einem viel niedrigeren Niveau. Die nach oben gerichteten Laserstrahlen mit > 50mW waren mir etwas zu gefährlich für die Schule (nette Ausrede, nicht?).

Funktioniert aber auch sehr gut. Einziger Wermutstropfen: Das Keyboard meiner Tochter ist leider seit letzter Woche entführt und wir haben nicht einmal eine Lösegeldforderung erhalten...

Anbei ein paar Bilder. Liebe Grüße und frohe Ostern, Christoph

[shrad]

hello!

a little tip for Genesis.. maybe remote control burst encoders/decoders with a modulation of several Khz would do the trick... if the modulation suits the lasers bandwidth, that would not be difficult to adapt a remote decoder in the photodiodes output ^^